Fault Tree Analysis For Automotive Performance Fuel Pump Circuit Fault Determination
Date: 2020-12-09 Clicks: 238
The flowchart is also drawn to improve the efficiency of judgment and repair.
Automotive electronic fault diagnosis methods are fault tree analysis, wavelet analysis, hierarchical analysis, neural network diagnostics, fuzzy diagnostics, etc. The main features of the automotive electronic fault diagnosis methods are fault tree analysis, wavelet analysis, hierarchical analysis, neural network diagnostics, fuzzy diagnostics. The more suitable for automotive electronic fault characteristics of the fault tree analysis, the key to the fault tree design, usually deductive method of tree building. However, the fault tree analysis results in multiple failure causes and failure sites, extending the maintenance time. Therefore, I improved the fault tree analysis, based on the designed fault tree, additional conditional rules, and further mathematical and logical diagnostic reasoning, greatly improving the fault diagnosis efficiency, especially for complex fault tree.
1 Automotive performance Fuel Pump circuit faults
Fault tree construction Take the Toyota Corolla sedan performance Fuel Pump does not run circuit failure as an example, to explain the process of fault tree construction. According to the performance Fuel Pump control principle, the circuit is controlled by the performance Fuel Pump power supply area C, the performance Fuel Pump control area D and the performance Fuel Pump working area B. Comparing the degree of difficulty in determining the fault, area B is easy, area C is the next easiest and area D is more difficult. The purpose of the repair is to make the performance Fuel Pump run, therefore, the performance Fuel Pump does not run as the top event of the node design, B, C, D working abnormally as an intermediate event to construct the fault tree.
2 Mathematical Basis Analysis
The fault tree is made up of all the intermediate events and the logical connections of the "inter" and "concurrent" events.
2.1 Setting up a Structural Function
Failure of the system is called the top event of the fault tree, denoted T. Failure of each component or some part of a component is called the bottom event. If only system and component states are considered, then the bottom event can be defined as: the i-th bottom event occurs, Xi = 1; the i-th bottom event does not occur, Xi = 0 . IfΦis used to represent the top event state of the system, thenΦmust be the bottom event state X i (i n = 1, 2, , " ) as a function ofΦ= 1 2 (, , , )ΦXX X " n ,Φ(X) is the structural function of the fault tree or the gate fault tree as 1Φ( ) = = =∑n i i i X . The fault tree in Figure 2, n=12, indicates that the number of constituent events is 12.
2.2 Fault Tree Qualitative Analysis
The purpose of a qualitative fault tree is to identify all possible failure modes that lead to a top event, and to figure out how many possibilities there are for an undesired event to occur in the system. If a set of several bottom events occurs that will cause a top event to occur, this set is called the minimum cut set, i.e., a cut set that represents a probability that a system failure will occur. If the set of several bottom events does not occur to guarantee that the top event will not occur, the set is called a road set. A road set represents the probability that the system will work. The set of cuts in a fault tree that is no longer a cut set if any one of the bottom events is removed is called a minimally cut set. Since the events in the least cut set occur when the top event must occur, the complete set of all the least cut sets in a fault tree represents all possibilities for the top event to occur.
2.3 Logic of Fault Tree Reasoning after Additional Conditional Rules
3 Determine flowchart design
It has been proven that using conditional rule-based fault tree analysis, combined with maintenance and production practices, to design a practical fault tree, reasonable adjustments, can greatly improve the efficiency of automotive fault judgments and improve the economic and social benefits of automotive repair operations. This method can prevent misjudgment and omission and improve the accuracy of fault judgment. Due to the differences in structure and control principle of different vehicle models, a targeted design of the fault tree and continuous testing of the fault tree through practice can greatly reduce the difficulty of fault diagnosis and maintenance. If all the designed fault tree collection into an expert library, with the help of the network, you can realize the car remote auxiliary judgment, or even build an expert judgment system.
This article is quoted from the Journal of Xinxiang College (Natural Sciences Edition).